% \PassOptionsToPackage{showframe}{geometry}
\documentclass{exam-zh}
\examsetup{
  % question/show-answer=true,
  % fillin/show-blacktriangle=true,
  % fillin/show-blacktriangle=false,
}

\begin{document}
\fillin
\fillin[]
\fillin[something]

\fillin[type=paren][]
\fillin[type=paren][something]

\end{document}